1. Field of the Invention
The present invention relates to a liquid crystal display panel, and more particularly, to a method for cutting a liquid crystal display panel. Although the present invention is suitable for a wide scope of applications, it is particularly suitable for cutting liquid crystal display panels having different sizes from large mother substrates.
2. Discussion of the Related Art
Generally, a liquid crystal display (LCD) device is a display device for displaying images by adjusting light transmittance of liquid crystal cells by individually supplying data signals corresponding to image information to the liquid crystal cells, which are aligned in a matrix form.
In the LCD device, a plurality of thin film transistor (TFT) array substrates are formed at a large mother substrate and a plurality of color filter substrates are formed at another mother substrate. Then, by attaching the two mother substrates, a plurality of unit LCD panels are formed and cut into unit LCD panels to improve yield.
Conventionally, the cutting process includes forming a scribing line on the surface of the mother substrate with a wheel having a hardness higher than the substrate and transmitting a crack along the scribing line. The cutting process of the unit LCD panels will be described in detail with reference to the accompanied drawings.
FIG. 1 is a schematic view showing a structure of a unit LCD panel formed in a thin film transistor array substrate and a color filter substrate attached to each other.
As shown in FIG. 1, an LCD panel 10 includes an image display unit 13 in which a plurality of liquid crystal cells are aligned in a matrix form, a gate pad unit 14 connected to gate lines of the image display unit 13 and a data pad unit 15 connected to data lines. At this time, the gate pad unit 14 and the data pad unit 15 are formed at the marginal portion of the TFT array substrates 1 that do not overlap the color filter substrates 2. The gate pad unit 14 supplies a scan signal which is supplied from a gate driver integrated circuit (IC) to the gate lines of the image display unit 13 and the data pad unit 15 supplies image information which is supplied from a data driver integrated IC to the data lines of the image display unit 13.
The data lines for applying image information and the gate lines for applying scan signals are arrayed to vertically cross each other on the TFT array substrate 1 of the image display unit 13. At the crossing portion, a TFT for switching the liquid crystal cells, a pixel electrode connected to the TFT for driving the liquid crystal cells, and a passivation layer are formed on the front surface of the TFT to protect the data lines, the gate lines, the pixel electrodes, and the TFT.
Also, on the color filter substrate 2 of the image display unit 13, color filters which are spread to be divided into respective regions by a black matrix. Also, a common electrode is formed to correspond to the pixel electrode formed on the TFT array substrate 1.
A cell-gap is formed so that the TFT array substrates 1 and the color filter substrates 2 oppose to each other and are regularly separated. The two substrates are attached by a sealant (not shown), which is formed at the circumference of the image display unit 13. In addition, a liquid crystal layer (not shown) is formed in a space between the TFT array substrates 1 and the color filter substrates 2.
FIG. 2 is a schematic cross-sectional view illustrating that a plurality of unit LCD panels are formed by attaching a first mother substrate where the TFT array substrates are formed, and a second mother substrate where the color filter substrates are formed.
With reference to FIG. 2, a side end portion of each TFT array substrate 1 is protruded more than that of the color filter substrate 2, since the gate pad unit 14 and the data pad unit 15 are formed at the marginal portion of the TFT array substrates 1 that do not overlap the color filter substrates 2, as described above.
Therefore, the color filter substrates 2 on the first mother substrate 20 are formed to be smaller than the TFT array substrates 1 as much as a dummy region 31.
Also, each unit liquid crystal panel is appropriately positioned to maximize the use of the first and second mother substrates 20 and 30. Generally, the unit liquid crystal panels are formed to be separated by a dummy region 32. A dummy region 21 for a process margin is also formed in the marginal portions of the first and second mother substrates 20 and 30.
After the first mother substrate 20 where the TFT array substrates 1 are formed and the second mother substrate 30 where the color filter substrates 2 are attached to each other, the attached substrates are cut into unit liquid crystal panels. At this time, the dummy region 31 formed at the color filter substrates 2 of the second mother substrate 30, the dummy region 32 for separating the unit liquid crystal panels, and the dummy region 21 formed at the marginal portion of the first and second mother substrates 20 and 30, are simultaneously removed from the attached substrates.
FIG. 3 is a schematic plane view illustrating that a plurality of unit LCD panels are formed on a large size mother substrate. As shown in the drawing, six LCD panels 110 are formed in the mother substrate considering the size of the mother substrate 100 and LCD panel 110.
In case of fabricating LCD panels with a larger size without increasing the size of the mother substrate 100, only three LCD panels 120 may be formed in the mother substrate 100 and the portion of the mother substrate 100 that the LCD panel is not formed is discarded, as shown in FIG. 4.
Therefore, efficiency in using the mother substrate 100 is degraded, thereby reducing productivity and increasing product cost.